Birch Reduction of Asphaltenes. Synthesis of Hydroasphaltenes

Abstract

Reduction of Ecuadorian asphaltenes by lithium in liquid ammonia (Birch conditions) yields asphaltene salts that can be protonated by tert-butyl alcohol to yield deflocculated hydroasphaltene. Studies were carried out using asphaltenes from both low-and high-viscosity oils. The dimensions of the hydroasphaltenes were determined by atomic force microscopy. Relative to the starting asphaltene, the nominal asphaltene aggregate height of the low-viscosity asphaltene 1 was reduced from 1.3 to 0.7 nm, indicating that the asphaltene was fully exfoliated. The height of the high-viscosity asphaltene 2 was reduced from 4 to 2 nm. 13 C nuclear magnetic resonance of the Birch-reduced asphaltenes shows a reduction in aromaticity from 49 to 46%, indicating that a low level of hydrogen was added to the aromatic core during the Birch reduction.